Field of the Invention
The invention relates to a carrier and a chip connected to the carrier. The carrier has a metal area on which the chip is configured.
It is known to produce circuit arrangements using hybrid technology. To that end, chips, without a chip housing and with semiconductor components, are electrically contact-connected and are fixed directly onto a ceramic carrier in which conductor tracks made of copper are arranged. The chips have rear side metallization layers that directly adjoin metal areas made of copper that are arranged on the carrier. The metal areas made of copper are connected to the conductor tracks. In order to protect the metal areas against oxidation, it is known to provide the metal areas with a protective layer made of nickel having a thickness of approximately 1 μm to 2 μm.
If such a circuit arrangement is exposed to a relatively large number of large temperature fluctuations, it has been shown that the connection between the carrier and the chips becomes so brittle that the heat arising in the power semiconductor components contained in the chips can no longer be adequately dissipated, which leads to the destruction of the chips. The effect is presumably based on the different thermal expansion coefficients of the metal areas and the rear side metallization layers.
There are many applications requiring circuit arrangements that have a high stability with respect to temperature fluctuations. This is the case, for example, when a circuit arrangement is used in a motor vehicle. Indeed in very cold regions, a circuit arrangement arranged e.g. in a starter generator must withstand a change in temperature from −40° C. to +160° C. within approximately 10 seconds when the motor vehicle is started. It is desirable for such a circuit arrangement to withstand at least 1000, better more than 2000, such temperature cycles without damage.